1. Field of the Invention
This invention relates to an agitator assembly for a vacuum cleaner, and in particular to an agitator assembly having apparatus for preventing dust from contaminating the bearings of the assembly.
2. Description of the Prior Art
Agitator assemblies or brush roll assemblies for use in vacuum cleaners are well known in the art. An agitator assembly generally includes a wooden dowel which is configured to be driven by a belt or a gear train, and has tufts of bristles and/or beater bar elements projecting radially from the surface of the dowel for beating against the surface of a carpet to loosen dirt from the fibers of the carpet. The agitator assembly rotates on bearings or bushings, and one of the problems with agitator assemblies used in vacuum cleaners is that dust tends to collect in and contaminate the bearings or bushings, detracting from the free rotation of the agitator assembly and leading to damage to the bearings. One of the means for protecting the bearings from dust is the use of a labyrinth thread seal to protect the bearings from dust, as is shown, for example, in U.S. Pat. No. 5,373,603. However, labyrinth seals are not entirely effective in use. It is also known to use dust shields for covering the end of the dowel to inhibit the path of the flow of dust into the bearing; however, such dust shields are also not entirely effective. Most agitator assemblies are made from wood and require both time to shape the dowel and the added step of balancing to achieve rotational stability.
An object of the present invention is to provide an agitator assembly, which is rotated in a vacuum cleaner on a set of bearings, with means for preventing dust from contaminating the bearing.
Another object of the invention is to provide an agitator assembly for a vacuum cleaner which expels dust, which dust may otherwise have gotten in or near the bearings.
Still another object of the invention is to provide an agitator assembly which is balanced when it is made and does not require any subsequent rotational balancing.
A yet further object of the invention is to provide an agitator assembly which can be produced efficiently and economically while yielding a device of high operational quality.
A further object of the invention is to provide an agitator assembly for a vacuum cleaner which employs the movement of air generated by the rotation of a dowel assembly to keep dust from impairing the operation of the bearing assembly used in the agitator assembly.
An additional object is to provide a system for reducing or preventing dust from contaminating the bearing assembly in the agitator assembly of a vacuum cleaner which requires a small number of parts.
Still another object of the invention is to provide an agitator assembly from which threads and other fibers can be easily removed once they have been wound on the brush roll of the agitator assembly as it rotates.
Other objects should be apparent from the description to follow and from the appended claims.
The foregoing objects are achieved according to the preferred embodiment of the invention. Accordingly, a vacuum cleaner agitator or brush roll assembly is provided having a central shaft or pin on which is mounted a belt drive pulley for receiving the drive belt from a vacuum cleaner. The agitator assembly incorporates a dowel from which tufts of bristles extend radially to loosen dirt from the carpet fibers. The dowel having the extending tufts is referred to as a brush roll. The central shaft of the agitator assembly extends along the longitudinal axis of the dowel and is rotated about the axis with the dowel by the belt from the vacuum cleaner. The dowel has an indented or recessed portion at each of its ends which are configured in a truncated fashion with inclined walls extending radially outwardly from the innermost end of the walls to the respective ends of the dowel. A set of radial vanes extend inwardly from the inclined walls towards the longitudinal axis. An end cap or cover in the form of a hub is fixed in the vacuum cleaner to which the agitator assembly is mounted and extends over each end of the dowel and has a collar extending into the recess for fixedly engaging the outer ring of the ball bearing assembly. The collar surrounds the ball bearing assembly and forms part of a labyrinth seal as well as defining part of an air passageway. The shaft fixedly engages the inner ring of the ball bearing assembly. The inner surface of the collar is cylindrical in format to engage the outer ring of the ball bearing assembly, while the outer surface of the collar is inclined to be generally parallel with the vanes of the dowel. The end cap has surfaces which are perpendicular to the longitudinal axis of the agitator assembly and extend across each end of the dowel and have an outer longitudinally-extending cylindrical portion which extends over the outer diameter of the dowel. The end caps and the recessed ends of the dowel with the radial vanes form a centrifugal dust shield as discussed below.
The dowel assembly has a drive member such as a pulley which is generally parallel to the outer cylindrical surface of the dowel and is configured to be driven by the belt of the vacuum cleaner. The location of the latter member can be varied according to the type of vacuum cleaner in which the agitator assembly is to be used. When the belt of the vacuum cleaner is rotating, it in turn rotates the pulley, the shaft and dowel, which in turn rotates the inner ring of the ball bearing assembly but the outer ring of the bearing assembly and the end cap are stationary relative to the dowel assembly. Therefore, the shaft rotates the inner ring of the ball bearing assembly at opposite ends of the agitator assembly.
During rotation, there are two occurrences relating to dust. First, the rotation of the dowel and the vanes produces turbulent air in the space between the vanes at the ends of the dowel and the end cap; and the turbulent air acts as a barrier to prevent dust from flowing between the end cap and the vanes of the dowel, to prevent the dust from contaminating the bearings. The second occurrence is that any dust, which is near the bearings or in the space between the end cap and the dowel, is thrown outwardly by centrifugal force, and the inclined ramp of the undercut portion of the dowel and the outer inclined portion of the collar of the end cap cooperate to cause the dust or dirt which is thrown outwardly by centrifugal force to be forced from the agitator assembly, and away the vacuum cleaner. Thus, the vanes establish an air barrier to the dust, and centrifugal force moves any dirt or dust outwardly along the path established by the recess in the dowel and the end cap. As a result, any damage that could be caused by the dust is avoided.
The dowel assembly according to the invention is made from plastic rather than from wood, and is so designed that it can be fabricated in a rotationally stable form. The production of the dowel is fast, accurate, and does not require the additional step of balancing the unit as was required in the prior art using wooden agitator assemblies. Cutting channels extend along the outer surface of the dowel to enable the cutting and removal of threads and other fibers wound thereon.